China successfully launches satellite to explore dark side of Moon

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PTI

May 21, 2018

UPDATED: May 21, 2018 15:00 IST

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By K J M Varma

Beijing, May 21 (PTI) China successfully launched a relay satellite today to enable a rover to communicate with the Earth from the Moons mysterious far side, as part of the Communist giants ambitious goal of being the first country to send such a probe.

Named Queqiao (Magpie Bridge), the 400-kg satellite has a designed life of three years.

It was carried by a Long March-4C rocket that blasted off at 5:28 AM (local time) from southwest Chinas Xichang Satellite Launch Center, the China National Space Administration (CNSA) said.

"The launch is a key step for China to realise its goal of being the first country to send a probe to soft-land on and rove the far side of the Moon," said Zhang Lihua, manager of the relay satellite project.

About 25 minutes after lift-off, the satellite separated from the rocket and entered an Earth-Moon transfer orbit with the perigee at 200 kms and the apogee at about 400,000 kms. The solar panels and the communication antennas were unfolded.

Queqiao is expected to enter a halo orbit around the second Lagrangian (L2) point of the Earth-Moon system, about 455,000 kms from the Earth.

It will be the worlds first communication satellite operating in that orbit, state-run Xinhua news agency reported.

The satellite carries several antennas. One, shaped like an umbrella with a diameter of five metre, is the largest communication antenna ever used in deep space exploration, said Chen Lan, deputy chief engineer of the Xian Branch of the China Academy of Space Technology (CAST).

The satellite could stay in the halo orbit around the L2 point of the Earth-Moon system for a long time by using relatively little fuel, thanks to the gravitational equilibrium at that point.

But the mission must overcome many challenges, including multiple adjustments to its orbit and braking near the Moon and taking advantage of the lunar gravity, Zhang said.

In a Chinese folktale, magpies form a bridge on the seventh night of the seventh month of the lunar calendar to enable Zhi Nyu, a weaver girl who is the seventh daughter of the Goddess of Heaven, to meet her beloved husband, cowherd Niu Lang. The couple were separated by the Milky Way.

Chinese scientists and engineers hope the Queqiao satellite will form a communication bridge between controllers on the Earth and the far side of the Moon where the Change-4 lunar probe is expected to touch down later this year.

Todays launch was the 275th mission of the Long March rocket series.

Tidal forces of the Earth have slowed the Moons rotation to the point where the same side always faces the Earth, a phenomenon called tidal locking.

The other face, most of which is never visible from the Earth, is the far side or dark side of the Moon, not because its dark, but because most of it remains unknown.

With its special environment and complex geological history, the far side is a hot spot for scientific and space exploration.

The Aitken Basin of the lunar south pole region on the far side has been chosen as the landing site for Change-4. The region is believed to have great research potential.

However, landing and roving require a relay satellite to transmit signals.

The Change-4 mission will be more complicated than Change-3, Chinas first soft landing on the Moon in 2013.

"We designed an orbit around the Earth-Moon L2 point where the relay satellite will be able to see both the Earth and the far side of the Moon," Bao Weimin, director of the Science and Technology Commission of the China Aerospace Science and Technology Corporation said.

Establishing a communication link is essential for the success of the Change-4 mission, Bao was quoted by Xinhua. PTI KJV CPS AKJ CPS CPS

This is unedited, unformatted feed from the Press Trust of India wire.

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